The present invention relates generally to a system for controlling rotational direction switchover and for variably controlling the rotational speed of a motor, and more particularly to a system capable of controlling rotational direction switchover and further of continuously and variably controlling the rotational speed of a motor through manual operation of a single control means.
In general, the operation of editing programs comprised of video signals recorded on magnetic tapes is carried out by recording on a new tape in continuous succession the desired program sections among the programs comprised of video signals recorded on one or more original tapes. In editing, the tape recorded with the program video signal to be edited is reproduced on a reproducing apparatus for electronic editing, and the position of the desired section is searched out by observing the reproduced picture. The reproduction is then carried out from the beginning of the desired section, and the resulting reproduced signal is recorded on the new tape by the recording apparatus.
For shortening the time required for locating the position of the desired section and then further locating the beginning of the section and causing the tape to stop at this beginning position on the reproducing apparatus for editing, it is desired that the tape runs at high speeds in the normal and reverse directions and that the tape running speed be reduced near the desired beginning position. For achieving this operation, the tape running speed must be changed during the tape running mode. Moreover, it is difficult to stop the tape at the desired beginning position through a single operation because the beginning position on the recorded tape generally cannot be recognized the moment it passes by. Accordingly, after the initial position on the tape has passed by, the tape runs in the opposite direction at low speed. By repeating this operation, the beginning of the desired program on the tape is located and the tape is finally stopped.
In this connection, the conventional type of reproducing apparatus for editing is provided with a switch button for switching over the rotational direction of a capstan motor for driving the tape to run between the normal rotational direction and the reverse rotational direction, that is, between normal and reverse tape traveling directions, and a plurality of switch buttons are provided for setting the rotational speed of the motor (that is, the tape traveling speed) to, for example, double speed, normal speed, 1/5 speed, 1/20 speed, and the like, so that both the tape traveling direction and the traveling speed can be changed through appropriate manipulation of these switch buttons.
Accordingly, in this known apparatus for editing reproduction, the manipulation of separate switch buttons is required in switching over the tape traveling direction (i.e., the rotational direction of the motor) and in changing the tape traveling speed (i.e., the rotational speed of the motor). Therefore, manual operational control of the conventional apparatus is very troublesome. Further, since the tape traveling speed must be selected among a plurality of preset speeds, the tape traveling speed cannot be varied continuously. Still further, the larger number of switches needed makes the apparatus complicated and expensive.